The Influence of Substrate Heterogeneity on Biofilm Metabolism in a Stream Ecosystem

Palmer, Margaret A.; Swan, Christopher M.; Brooks, Shane; Poff, N. LeRoy

doi:10.2307/2680024

Cited by 78 publications

(117 citation statements)

References 49 publications

(81 reference statements)

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“…These results provided the first support for the widely held assumption that physical heterogeneity controls resource use, and even the diversity of resources used, in stream biofilms. The findings also corroborated an older study that examined stream reaches in which near-bed flow velocity and turbulence intensity fluctuated, which demonstrated that habitat heterogeneity influences the primary productivity and respiration of benthic biofilms 92 .…”

supporting

confidence: 76%

The ecology and biogeochemistry of stream biofilms

et al. 2016

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The perception that most microorganisms live as complex communities that are attached to surfaces has profoundly changed microbiology over the past decades. Most, if not all, bacteria can form biofilms, which are communities of cells embedded in a porous extracellular matrix.Dental plaque, the microorganisms on catheters and implants that cause persistent infections and the fouling of ship hulls and pipework are all examples of biofilms with important implications for public health and industrial processes. Most contemporary biofilm research rests on the discovery made more than 35 years ago by Maurice Lock, Gill Geesey and Bill Costerton: bacteria attached to surfaces dominate microbial life in streams [1][2][3] . These microbiologists pioneered research into stream biofilms, also termed periphyton or epilithon, and described them as complex aggregates of bacteria, algae, protozoa, fungi and meiobenthos. The early study of stream biofilms also highlighted the relevance of interactions between microbial phototrophs and heterotrophs for energy fluxes and the role of the biofilm matrix as the site of extracellular enzyme activity and adsorption of dissolved organic matter (DOM) 3,4 .Since these early days, the study of the ecology and biogeochemistry of stream biofilms has slowly developed in the wake of thriving research on bacterial biofilms -often comprising 3 only a single strain, of interest to medical microbiology, rather than the polymicrobial communities found in stream biofilms -and on the microbial ecology of marine and lake planktonic communities 5 . Unlike bacterial biofilms grown in the laboratory, biofilms in streams are continuously exposed to a diverse inoculum that includes bacteria, archaea, algae, fungi, protozoa and even metazoa. These diverse biological 'building blocks', when combined with the dynamic flow of streamwater, generate biofilms with inherently complex and varying physical structures that have implications for microbial functioning and ecosystem processes 6 . In streams, biofilms are key sites of enzymatic activity 7 , including organic matter cycling, ecosystem respiration and primary production and, as such, form the basis of the food web.Why should we study the ecology and biogeochemistry of stream biofilms? Streams sculpt the continental surface, forming dense and conspicuous channel networks that can be thought of as ecological arteries that perfuse the landscape. Streams are connected to their catchments through various surface and subsurface flow paths and notably through the hyporheic zone in the streambed at the interface between groundwater and streamwater 8 . Microbial cells, solutes and particles enter streams through these flow paths and, en route to downstream ecosystems and ultimately to the oceans, they may interact with the biofilms that colonize the large surface area provided by the streambed as a 'microbial skin' (BOX 1). As a result, the streambed and its biofilm microbiome contribute to biogeochemical fluxes 8 . Indeed, stream biofilms are now recognized as su...

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supporting

confidence: 76%

The ecology and biogeochemistry of stream biofilms

et al. 2016

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“…The colonisation, conditioned and enumeration trays were deployed on a large riffle in the River Soar, Leicestershire UK (1° 11.0' W, 52° 46.8' N) for 21 days in July - August 2006. This period provided sufficient time for colonisation and is consistent with other investigations that consider substrate colonisation by benthic macroinvertebrates (Mackey, 1992;Cardinale et al, 2002). The riffle has a relatively uniform geomorphic and hydraulic environment and supports high densities of several hydropsychid caddisfly larvae species Deployment of trays was staggered so that entrainment measurements for a particular tray could be made in the flume on the same day that the tray was removed from the river.…”

Section: Field Proceduressupporting

confidence: 64%

Stabilization of fine gravels by net‐spinning caddisfly larvae

Johnson

Reid

Rice

et al. 2009

Earth Surf Processes Landf

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We examined the impact of Hydropsychidae caddisfly larvae on the incipient motion of two sizes of narrowly graded fine‐gravel (4–6 and 6–8 mm). This impact was assessed relative to the collective impact of other abiotic and biotic processes that are potentially important conditioning agents of fine‐gravels. Trays of gravel were placed in the River Soar, Leicestershire, UK, where they were colonized to natural densities by caddisfly larvae. Identical trays that were surrounded by a 250 µm mesh were also deployed, preventing colonization but allowing field conditioning of sediments, including minor reworking of grains and biofilm development. After 21 days in the river, trays were removed to a laboratory flume where grain entrainment stresses were established. In addition to the colonized and conditioned treatments, critical shear stresses were measured for identical sediments that were not placed in the river (laboratory gravels). Gravels that were colonized by Hydropsychidae required significantly greater shear stresses for entrainment than conditioned trays (p ≤ 0·002), however, there was no significant difference between conditioned and laboratory gravels. This implies that the presence of caddisfly can be a more important influence on fine‐gravel stability than some conditioning processes. Shields parameter was compared across treatments and across the two gravel size‐fractions using two‐way ANOVA. No significant differences or interactions were observed, indicating that 4–6 mm gravel was stabilized to a similar degree as 6–8 mm gravel by conditioning and colonization processes. Our results extend earlier studies in two important ways: (1) entrainment stresses were established for fine gravels that were colonized at natural densities, under natural stream conditions; and (2) the caddisfly effect was measured relative to both field‐conditioned and unconditioned laboratory controls. The temporal and spatial distribution of silk‐spinning caddisfly larvae suggests that they have the potential to influence fine‐sediment mobility in many rivers, worldwide. Copyright © 2008 John Wiley & Sons, Ltd.

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“…Similar to reductions in anadromous fish populations, the homogenization of river ecosystems is widespread (Cardinale et al 2002), so increasing PHS by adding wood or large boulders is a popular method of restoring this lost complexity (Roni and Quinn 2001, Lepori et al 2005, Roni et al 2008. Clearly, many aquatic ecosystems would benefit from restoration of habitat complexity; unfortunately, these efforts may not improve demographic rates of threatened species, especially in resource-limited systems, if PHS also intensifies density-dependent interactions by aggregating organisms.…”

Section: Synthesis and Implicationsmentioning

confidence: 99%

“…For instance, fish abundance and diversity was higher in stream pool habitats with wood, possibly because of increased resource availability and protection from predators (Wright and Flecker 2004). As with resource pulses though, we have a relatively limited mechanistic understanding of how PHS shapes ecosystems (Kovalenko et al 2012, except see Cardinale et al 2002) including how it influences the movement of organisms through the environment, a key ecological process (Gaines and Bertness 1993, Bowler and Benton 2005, Kuefler et al 2010. For example, PHS may modify drift, or the downstream movement of invertebrates in the water column (Benke et al 1986).…”

Section: Introductionmentioning

confidence: 99%

Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment

et al. 2014

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An experiment and a mark‐recapture field study of juvenile coho salmon (Oncorhynchus kisutch) were conducted to identify controls of key energy flow chains in river food webs. In the small‐scale experiment, we investigated the individual and interactive effects of physical habitat structure (PHS) as small wood and resource availability (tissue of adult Chinook salmon, O. tshawytscha) on nutrients, algae, invertebrates, and fish predators including juvenile coho. In the field, we quantified the effects of natural variation in prey availability (invertebrate drift biomass), PHS (wood), and local fish density on summer growth of juvenile coho across multiple stream reaches. Adding salmon tissue to experimental channels resulted in strong bottom‐up effects on select invertebrates including increased population biomass of chironomids and baetids, the numerically dominant invertebrates, and faster growth of juvenile coho. We link the enhanced growth of coho to chironomid productivity: for instance, adult chironomid flux was 4.3× higher and coho consumption of these animals 3× higher in salmon‐subsidized channels. PHS in experimental channels was associated with reduced algal biomass, potentially in response to increased invertebrate consumption, and invertebrate flux or export. The field study revealed coho growth was negatively related to PHS and total fish density and positively related to Diptera drift biomass; however, the effects of fish density and drift biomass on coho growth were relatively weak. The field study also indicated that prey resource availability and coho growth were associated with differences in canopy cover, with prey biomass and coho growth 2–4× higher in reaches receiving more sunlight. As in the experiment, coho in natural stream reaches predominantly fed on adult chironomids and other Diptera, indicating that these taxa and life‐stages are a key link between the benthic food web and mobile vertebrate predators. Our study showed that bottom‐up processes initiated by salmon subsidies and possibly light flux determined key trophic interactions in the Cedar River food web. Moreover, we speculate that PHS may modify some of these interactions indirectly through its effects on the movement of organisms through the environment.

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The Influence of Substrate Heterogeneity on Biofilm Metabolism in a Stream Ecosystem

Cited by 78 publications

References 49 publications

The ecology and biogeochemistry of stream biofilms

The ecology and biogeochemistry of stream biofilms

Stabilization of fine gravels by net‐spinning caddisfly larvae

Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment

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